JP7519552B2 - Push button switch parts - Google Patents

Description

Cross References

This application claims priority based on Japanese Patent Application No. 2021-147279 filed in Japan on September 10, 2021, the contents of which are incorporated herein by reference. In addition, the contents of the patents, patent applications, and literature cited in this application are incorporated herein by reference.

The present invention relates to a component for a push button switch.

Push button switch components having a pressing portion, a dome portion and a base portion have been used as switches for a wide variety of devices, such as in-vehicle devices, communication devices, audio devices and household electrical appliances (see, for example, Patent Document 1).

Figure 5 shows a longitudinal cross-sectional view of a conventionally known push button switch component.

The push button switch member 100 shown in Fig. 5 comprises a key top 111, a dome portion 112 that expands in diameter at a constant rate from the bottom end of the key top 111, a base portion 113 that is fixed to an opening in the dome portion 112 located on the opposite side to the key top 111, and a protrusion portion 114 that is located directly below the key top 111 and protrudes into the space within the dome portion 112. The push button switch member 100 is a member that causes the dome portion 112 to buckle and deform when the key top 111 is pressed toward the base portion 113, i.e., vertically downward from the key top 111 in Fig. 5, and enables the dome portion 112 to return to its original shape when the pressing of the key top 111 is released.

When pressing begins on the key top 111 of a conventionally known push button switch member 100, the dome portion 112 buckles and deforms, and then the load decreases, followed by a load-displacement curve (FS curve) 150 until the load reaches a minimum value. Then, when comparing angle A from the initial point where pressing begins to the peak point where the load reaches a maximum value and angle B from the peak point to the make point where the load reaches a minimum value, A≦B.

JP 2000-76959 A

However, in the above-mentioned conventionally known push button switch member 100, the load required for the protruding portion 114 to contact the substrate or the like after the dome portion 112 buckles and deforms is relatively large, and the feeling of pressing is not good. In particular, now that in-vehicle applications in luxury cars have increased, there is a demand for improved operability and a clearer feeling of pressing down.

The present invention has been made in consideration of the above problems, and aims to provide a component for a push button switch in which the resistance drops sharply after the push button is pressed down to a maximum load, allowing for a clear depression.

(1) In order to achieve the above object, a member for a push button switch according to one embodiment comprises:
Key tops and
A dome portion that expands in diameter from one end of the key top;
a base portion fixed to an opening in the dome portion located on the opposite side to the key top, wherein the dome portion is buckled and deformed when the key top is pressed toward the base portion, and the dome portion returns to its original shape when the pressing of the key top is released,
In a load-displacement curve from the start of pressing the key top through the buckling deformation of the dome portion to the point where the lower part of the key top abuts against the fixed part on its extension, a second angle from the peak point to the make point where the load reaches a minimum value is smaller than a first angle from the initial point where pressing the key top begins to the peak point where the load reaches a maximum value.
(2) In a member for a push button switch according to another embodiment, preferably, a ratio of the height of the key top to the width in a vertical section of the member for a push button switch may be set to be 0.5 or more and 7.00 or less.
(3) In a push button switch member according to another embodiment, the ratio of the height to the width of the key top may be preferably 0.75 or more and 6.75 or less.
(4) In a push button switch member according to another embodiment, the ratio of the height to the width of the key top may be set to be equal to or greater than 2.50 and equal to or less than 5.50.

According to the present invention, it is possible to provide a component for a push button switch in which the resistance drops suddenly after the push button is pressed down to a maximum load, allowing for a clear depression.

FIG. 1 is a vertical cross-sectional view of a member for a push button switch according to an embodiment of the present invention. FIG. 2 shows two examples of load-displacement curves of the push button switch member of FIG. FIG. 3 shows the FS curves of the 28 samples in Table 1. 4A to 4C are vertical cross-sectional views showing various modified examples of the push button switch member of FIG. FIG. 5 shows a vertical cross-sectional view of a conventionally known member for a push button switch.

1, 1a, 1b, 1c...push button switch member, 11...key top, 12...dome portion, 13...base portion, A...first angle, B...second angle.

Next, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described below does not limit the invention according to the claims, and not all of the elements and combinations thereof described in the embodiment are necessarily essential to the solution of the present invention.

Figure 1 shows a longitudinal cross-sectional view of a member for a push button switch according to an embodiment of the present invention. Figure 2 shows two examples of load-displacement curves of the member for a push button switch of Figure 1. In this application, the cut surface when cutting from the top surface of the key top in the direction in which the key top is pressed is referred to as the "longitudinal cross section."

The push button switch member 1 according to this embodiment comprises a key top 11, a dome portion 12 that expands in diameter at a constant rate from one end of the key top 11 (the lower end in FIG. 1), and a base portion 13 that is fixed to an opening in the dome portion 12 that is located on the opposite side of the key top 11. The push button switch member 1 preferably further comprises a protrusion 14 that is located directly below the key top 11 and protrudes into the space within the dome portion 12. The protrusion 14 may or may not have a conductive member at its tip. The push button switch member 1 can be used by fixing the base portion 13 to a fixed portion such as a circuit board. The circuit board is an example of a fixed portion on an extension of the lower portion of the key top 11. It is also possible to adopt a fixed portion other than a circuit board.

The push button switch member 1 is an elastic member that buckles and deforms the dome portion 12 when the key top 11 is pressed toward the base portion 13, and returns the dome portion 12 to its original shape when the key top 11 is released from the pressed state. The push button switch member 1 is an integrally molded product made of a rubber-like elastic body, but may also be a composite product in which the key top 11, dome portion 12, and base portion 13 are separate bodies.

Suitable examples of the rubber-like elastic body constituting the push button switch member 1 include thermosetting elastomers such as silicone rubber, urethane rubber, isoprene rubber, ethylene propylene rubber, natural rubber, ethylene propylene diene rubber, nitrile rubber (NBR) or styrene butadiene rubber (SBR), thermoplastic elastomers such as urethane-based, ester-based, styrene-based, olefin-based, butadiene-based and fluorine-based elastomers, or composites of the above. Of these rubber-like elastic bodies, silicone rubber is particularly preferred. The rubber-like elastic body may also contain a filler such as silica.

The push button switch member 1 is a member for a push button switch in which, on a load-displacement curve from the start of pressing the key top 11, through the buckling deformation of the dome portion 12, to the point where the lower portion of the key top 11, i.e., the tip of the protrusion 14, abuts on a fixed portion on its extension line, a second angle B from the peak point to the make point where the load reaches a minimum value is smaller than a first angle A from the initial point where pressing the key top 11 begins to the peak point where the load reaches a maximum value.

The push button switch member 1 preferably has a ratio (X/Y) of the height (X) to the width (Y) of the key top in the longitudinal section of the push button switch member 1, which is 0.50 or more and 7.00 or less. When X/Y is close to 0.50, the load-displacement curve (also called the FS curve) becomes like the FS curve 20. By making X/Y 0.50 or more, the first angle A becomes larger than the second angle B. As a result, the operator can be given a sudden change in the load on the operator's finger. As a result, the operator can be given a sudden change in the load on the operator's finger. The reason why the first angle A becomes larger than the second angle is as follows. The larger X is, the more difficult it is for the key top to bend when pressed and the less force is applied to the dome, so the peak point becomes longer. Therefore, the first angle A becomes larger. Also, the amount of displacement after the peak becomes shorter by the amount that the peak point is extended. As a result, the second angle B becomes smaller. When X/Y becomes even larger, the second angle B becomes smaller than the first angle A, as shown in the FS curve 30. As a result, the resistance applied to the operator's finger after the dome portion 12 buckles becomes even smaller, providing the operator with a good pressing sensation. When X/Y is equal to or greater than 7.00, the second angle B becomes almost constant. On the other hand, the larger X/Y becomes, the more difficult it becomes to press the key top 11 downward. For this reason, the upper limit of X/Y is 7.00.

In this application, the width (Y) means the diameter if the key top 11 is a cylinder or a cylinder, the major axis if the key top 11 is an elliptical cylinder, and the longest diagonal if the key top 11 is a rectangular cylinder. The height (X) generally means the length from the top surface of the key top 11 to the inner edge of the dome portion 12.

The push button switch member 1 preferably has an X/Y ratio of 0.75 or more and 6.75 or less. When X/Y is 0.75 or more, the operator is more likely to feel a clearer reduction in load after the dome portion 12 buckles and deforms. When X/Y is 6.75 or less, the key top 11 is more likely to be pressed downward. Furthermore, the push button switch member 1 more preferably has an X/Y ratio of 2.50 or more and 5.50 or less. When X/Y is 2.50 or more, the operator is even more likely to feel a clearer reduction in load after the dome portion 12 buckles and deforms. When X/Y is 5.50 or less, the key top 11 is even more likely to be pressed downward.

Next, 28 push button switch components 1 with different X/Y ratios were prepared and the FS curves were examined.

Table 1 shows the first angle A, the second angle B, and the pass/fail judgment of the F-S curve of 28 samples with different ratios of keytop height (X) and width (Y). Figure 3 shows the F-S curve of the 28 samples in Table 1. In Table 1, NG indicates failure, B indicates the third highest pass, A indicates the second highest pass, and AA indicates the first highest pass. NG means that the pressing sensation is poor. B, A, and AA all indicate a good pressing sensation, with AA indicating the best pressing sensation. In Figure 4, the maximum and minimum values of the F-S curve move to the right side of the graph as X/Y changes from 0.25 to 7.00. For some samples in the graph (1, 2, 3, 20, 21, 22, 23, 24, 18), the F-S curve is indicated by a dotted leader line. The FS curve shows the load and vertical displacement during the period when the top surface of the key top 11 is pressed at a speed of 1 mm/sec, the load reaches a maximum from the start of pressing, the load reaches a minimum as the dome part 12 buckles and deforms, and the load increases as the protrusion part 14 touches the ground. A 1605KL made by Aiko Engineering Co., Ltd. was used to press the key top 11.

The push button switch member 1 shown in Table 1 is a member obtained by kneading 500 g (100 parts by mass) of a curable silicone rubber composition (product number: KE-9611U) manufactured by Shin-Etsu Chemical Co., Ltd. and 50 g (1 part by mass) of a crosslinking agent (product number: C-8B) manufactured by the same company, sheeting the mixture, forming it into a sheet, dividing it into small portions, and placing the small portions into mold cavities corresponding to each X/Y ratio and curing them. The curing conditions were 180°C x 4 min. The key top 11, dome portion 12, base portion 13, and protrusion portion 14 are all integrally molded products made of silicone rubber. The width Y of the key top 11 of each push button switch member 1 was unified at 4 mm. The height X of the key top 11 was changed in increments of 1 mm in the range of 1 to 28 mm. The shape of the key top 11 was cylindrical. The dome portion 12 is a straight dome having an outer shape of a truncated cone with an average thickness of 0.46 mm, an inclination angle of 60 degrees, and a height of 1.2 mm. The base portion 13 is connected to the end face of the dome portion 12 with the widest diameter, and has a circular ring shape with a thickness of 1.5 mm and a width of 4.5 mm.

As is clear from Table 1, in sample No. 1 (X/Y = 0.25), the second angle B of the F-S curve was larger than the first angle A, and the push button switch member 1 had a poor pressing sensation. On the other hand, in samples No. 2 (X/Y = 0.50) to No. 28 (X/Y = 7.00), the first angle A of the F-S curve was equal to or smaller than the second angle B, and the push button switch member 1 had a good pressing sensation. In particular, samples No. 3 (X/Y = 0.75) to No. 27 (X/Y = 6.75) had a better pressing sensation than samples No. 2 (X/Y = 0.50) and No. 28 (X/Y = 7.00). Furthermore, samples No. 10 (X/Y = 2.50) to No. 22 (X/Y = 5.50) had a better pressing sensation than samples No. The pressing sensation was superior to samples No. 3 (X/Y=0.75) to No. 9 (X/Y=2.25) and samples No. 23 (X/Y=5.75) to No. 27 (X/Y=6.75).

Figure 4 shows vertical cross sections of various modified examples of the push button switch member of Figure 1.

Push button switch member 1a is a member having a recess 40 opening on the top surface of the key top 11 of push button switch member 1 in Fig. 1. Push button switch member 1b is a member in which a step 50 is provided midway through the key top 11 of push button switch member 1 in Fig. 1, and two columnar parts of different widths are overlapped on the upper part of the dome part 22. Push button switch member 1c is a member having a recess 40 opening on the top surface of the key top 11 of push button switch member 1b. Like these push button switch members 1a, 1b, and 1c, the key top 11 may be hollow and/or have a multi-stage structure.

The above describes preferred embodiments of the present invention, but the present invention is not limited to these and can be implemented in various modifications.

For example, the protrusion 14 may not be provided. Also, a conductive member may not be provided at the tip of the protrusion 14. The dome portion 12 may be a portion that rapidly buckles during the stroke until the protrusion 14 or the lower end surface of the key top 11 contacts a fixed portion such as a circuit board.

The push button switch component of the present invention can be used to construct push button switches for use in various devices equipped with push keys, such as automobiles, in-vehicle electronic devices, portable communication devices, personal computers, cameras, home audio equipment, and household electrical appliances.

Claims (1)

Key tops and
A dome portion that expands in diameter from one end of the key top;
a base portion fixed to an opening in the dome portion located on the opposite side to the key top, wherein the dome portion is buckled and deformed when the key top is pressed toward the base portion, and the dome portion returns to its original shape when the pressing of the key top is released,
In a load-displacement curve from the start of pressing the key top through the buckling deformation of the dome portion to the point where the lower portion of the key top abuts on a fixed portion on the extension line of the key top, a second angle from the peak point to a make point where the load reaches a minimum value is smaller than a first angle from an initial point where pressing the key top begins to a peak point where the load reaches a maximum value,
A member for a push button switch, wherein in a longitudinal section of the member for a push button switch, a ratio of height to width of the key top is 2.50 or more and 5.50 or less.